The present invention relates in general to an apparatus and method for fabricating structural components. More particularly, this invention concerns an apparatus and method for assembling pre-cut members into trusses and joists and splicing pre-cut members into truss chords.
Prefabricated trusses for use as roof or floor supports are assembled from pre-cut wooden chord and web members positioned in abutting relationship and connected together using toothed fastener plates. Where the length of the desired truss exceeds the length of readily available wood members, it is necessary to splice, or connect, multiple members in end-to-end abutment to create a single expanse of wooden chord.
Separate truss assembly and splicing devices have been developed for performing these tasks semi-automatically. In a truss assembly device, the pre-cut wooden members are positioned manually over a rigid support surface, then jigged or clamped in place. Connector plates then are laid over the abutting joints of the wooden members. The connector plates are then embedded into the members with a gantry or other roller press to secure the joints on one side. The gantry press typically has a single roller which passes over the truss assembly, thereby squeezing the truss assembly between the table surface and the roller. The semi-complete truss is then turned over and similarly secured at the joints on the opposite side with another set of connector plates. The gantry roller and truss table are shown in detail in U.S. Pat. Nos. 5,211,108 and 4,084,498 and in co-pending application Ser. No. 09/416,862, filed Oct. 13, 1999 by David McAdoo and Michael Rosser, the disclosure of which is incorporated herein by reference for all purposes.
In a typical splicing device, two wooden members are joined together in end-to-end abutment. Splicing of wooden members using a gantry press table having a single roller passing over a rigid table surface has been unsatisfactory, resulting in bowed, bent or cambered spliced chords, as shown in FIGS. 1 and 2. Chord members 2, spliced together at end-joint 8 on table surface 4 by gantry roller 9, are held together by connector plates 6. After the plates 6 are pressed into the chords 2, the spliced chords exhibit an undesirable bow, as seen in FIG. 2.
Typically, splicing and truss assembly operations occur on separate machines. Chord members are spliced together in one location within a facility, then laboriously moved to a truss assembly device where they are incorporated into a truss assembly. This process requires time, space and labor.
There exists a need for a new and improved truss assembly and splicing apparatus.
In accordance with the principles and concepts of the invention, apparatus and methods for assembling pre-cut members into trusses and joists and splicing pre-cut members into truss chords are presented. According to the invention, a splicing apparatus for connecting chord members end-to-end comprises a table having a table surface for supporting abutting chord members, a gantry press mounted adjacent to the table surface and configured to move relative to the table surface, the gantry press having at least two press rollers, each press roller having a peripheral surface positioned a successively closer clearance distance to the table surface. The splicing apparatus may further comprise at least two abutting chord members supported on the table surface, the chord members forming end-joints at each abutment and at least one connector plate positioned above each end-joint whereby each of the press rollers presses the connector plates at least partially into the chord members as the gantry press moves relative to the table surface. The apparatus may further comprise at least one connector plate positioned below each end-joint. The press rollers may be adjustable whereby the clearance distances of the peripheral surfaces of the press rollers above the table surface can be adjusted. The splicing apparatus may also comprise a truss assembly table.
The chord members are spliced together, end-to-end, by placing multiple wooden chord members in end-to-end abutment on the table surface, the chord members having end-joints at each end-to-end abutment, placing at least one connector plate over each end-joint, and pressing the connector plates into the chord members with a gantry press supported above the table surface and configured for movement relative to the table surface. The gantry press has a plurality of press rollers, each press roller having a peripheral surface positioned successively closer to the table surface, each press roller incrementally pressing the at least one connector plate into the chord members. The method may further comprise placing at least one connector plate under each end-joint between chord members. The clearance distances of the press roller peripheral surfaces may be adjusted.
Further according to the invention is presented a truss assembly and chord splicing apparatus combination having a table with a truss assembly surface for supporting a truss assembly, a splicing surface for supporting abutting chord members and a gantry press assembly mounted adjacent to the table and configured to move relative to the table, the gantry press assembly having a primary press roller configured to move over the truss assembly surface and at least two splicing press rollers configured to move over the splicing surface, the at least two splicing press rollers each having a peripheral surface positioned successively closer clearance distances above the splicing surface. The truss assembly may also have a plurality of abutting truss members positioned on the truss assembly surface forming truss joints at each abutment and abutting chord members supported on the splicing surface, the chord members forming end-joints at each abutment. A connector plate is positioned above each joint. Connector plates may be positioned under the chord joints. The primary press roller may further be configured to move over the splicing surface. The truss assembly surface and the splicing surface may be different heights above a floor surface.
Further is presented a truss assembly and chord splicing apparatus comprising a truss assembly table having a truss assembly surface and a splicing surface with a gantry press having a primary press roller and a splicing subassembly, the subassembly comprising at least two splicing press rollers, the splicing press rollers each having a peripheral surface positioned a successively closer clearance distance above the splicing surface.